The invention relates to the field of RF switches, and in particular to capacitive and DC types of RF switches having lower switch actuation thresholds, reduced field-induced stiction, and lower DC contact resistance.
A single RF capacitive switch in a coplanar waveguide can be comprised of a 200 μm long and 150 μm wide film of silicon dioxide and aluminum which forms a cantilever membrane. Stress is built into the membrane that causes it to curl upward away from a substrate. Moreover, the membrane includes a 50 μm long and 150 μm wide section at its end that forms one plate of a capacitor or moving plate. A voltage is applied between a buried electrode in the substrate and the membrane, which causes the membrane to pull and bring the moving plate into intimate contact with a similarly sized fixed electrode. This results in increasing the capacitance between the fixed electrode and moving plate.
A DC RF switch has a similar design except that the membrane is shorter, narrower, and has platinum contacts at the end of its curled up membrane. Also, the DC RF switch includes a platinum fixed contact on the surface of the substrate. With applied voltage, the moving platinum contact is brought in contact with the fixed platinum contact on the surface of the substrate, closing the DC circuit.
However, there is a need to have enhancements in both DC and capacitive switches that target lower switch actuation thresholds, reducing field-induced stiction, enabling x-y addressability in switch arrays, and dual-mode DC/capacitive switches.